The invention relates to the devices for any cigarette quality control to be effected at the hopper for the cigarette feeding to a cigarette-packing machine, the said hopper comprising in its lower section a set of cigarette-guiding down channels set side by side, which are adapted for containing each only one individual pile of cigarettes, so as to allow them to slide downward, and which are directed toward an underlying chamber within which there is formed a cigarette batch consisting of at least one layer of cigarettes set side by side, and being ejected therefrom by a pusher member at time intervals, to be transferred to the cigarette-packing machine. In correspondence of each one of the said cigarette-guiding channels, cigarette inspection sensor means are provided either on one or on both of the cigarette end sides, the said sensors being responsive to the cigarette property to be checked, and controlling cigarette ejection means that are adapted for ejecting and discarding any cigarette found out as defective through the quality control operation.
Any desired cigarette quality control may be effected, and it may, for example, concern the degree of filling of one or both of the cigarette ends, and/or the presence of the filter tip, and/or the air-retaining quality of the cigarettes, and/or the density of their tobacco filler, and/or the soundness of their wrapper, and/or the degree of ventilation or any other quality of the cigarettes.
A cigarette quality control device of the above type is known from the U.K. patent application No. 2.073.576. In this device, the cigarette quality control by the respective sensor means is effected during the dwell interval between two successive downward steps of the cigarette piles through the cigarette-guiding channels in the hopper, everytime during the ejection of a cigarette batch from the chamber at the bottom of said cigarette-guiding channels. For each cigarette-guiding channel two superposed parallel feeler pins are provided on at least one, but preferably on either one of the cigarette end sides, the said feeler pins being movable transversely to the respective cigarette-guiding channel in the longitudinal direction of the cigarettes, in such a manner that they will each time get co-axially close to the ends of two consecutive cigarettes in the cigarette pile within the respective cigarette-guiding channel, and will thus effect the inspection of both cigarettes. For the rejection of the defective cigarettes a pneumatic ejector nozzle (blower) is employed, arranged in correspondence of each cigarette-guiding channel in the hopper, downstream of the respective feeler pins and co-axially to the position taken by the cigarettes after every downward step of the cigarette pile.
In the known device of the above-disclosed type, the cigarette quality control is effected at each cigarette-guiding channel in the hopper on two successive cigarettes in the cigarette pile, whereby it is prevented that a cigarette might come down by a step before being checked, and might thus elude its quality control in the case of ejection of one underlying cigarette having been found out as defective through a preceding quality control operation, which would otherwise occur, should the quality control be effected at one single location, that is in correspondence of the position of only one cigarette in the pile. Accordingly, by adopting a quality control through two superposed feeler pins spaced apart by a distance corresponding to one downward step of the cigarettes, a cigarette having eluded the inspection by the upper feeler pin during one operative cycle in which a defective cigarette is being expelled downstream of the feeler pins, and the whole cigarette pile is being lowered by one step, will be inspected by the lower feeler pin during the subsequent operative cycle.
The above-disclosed known device however has the drawback of failing to check one cigarette whenever two consecutive defective cigarettes in the pile will be ejected. In this case, in order to prevent any failure in the quality control, inspection means should be provided in correspondence on three successive positions of the cigarettes, beside each one of the cigarette-guiding channels in the hopper. However, also in this case the quality control of one cigarette would fail to be effected, should three consecutive defective cigarettes be cast away from the cigarette pile. This is a serious disadvantage when considering that especially at the high output rates of the present cigarette-packing machines, a slight defect in the cigarettes, due to any transient cause, might occur in a relatively great number of cigarettes.